1. Field of the Invention
The present invention relates to a flat-shaped battery such as button type batteries and coin type batteries.
2. Description of Related Art
Flat-shaped batteries are used as power sources for various small-sized devices. For example, as shown in Patent Documents 1-5, the flat-shaped battery is so constructed that while a positive material and a negative material, which are electrode materials, are opposed to each other with a separator interposed therebetween, the electrode materials are housed in a battery case having a positive case and a negative case. The positive material is made by, for example, pressure forming of a positive mixture containing powdery manganese dioxide or the like. Therefore, the positive material has a characteristic of being relatively brittle, so that it is difficult to fix the positive material to the inner surface of the positive case of the battery case with the use of electroconductive adhesive or the like. Accordingly, the positive material is housed in the battery case as it is placed on the inner surface of the positive case.
Such a conventional flat-shaped battery is so devised that contactability between the positive material and the inner surface of the battery case is enhanced to thereby suppress deterioration in discharge performance. For instance, in the flat-shaped batteries of Patent Documents 1-5, it is proposed that with a spring or the like placed on the bottom face of the positive case, the positive material is pressed against the negative material side by the biasing force of the spring or the like to ensure the contactability between the positive material and the inner surface of the battery case.    Patent Document 1: JP H3-22346 A (FIG. 1)    Patent Document 2: JP S61-133571 A (FIGS. 1-2)    Patent Document 3: JP S63-175345 A (FIG. 1)    Patent Document 4: JP H6-7493 B (FIG. 3)    Patent Document 5: JP S63-6984 B (FIG. 2)